Packaging machines are known that integrate into a single unit the various components necessary to form a container, fill the container with a liquid product, and seal the container. Such packaging machines typically feed carton blanks into the machine, seal the bottoms of the cartons, fill the cartons with a product dispensed from a product storage tank through a filling tube, seal the tops of the cartons, and off-load the filled cartons for shipping.
Where the liquid product dispensed into the cartons is a liquid foodstuff it may be necessary to maintain a sterile filling environment. The sterile filling environment must be maintained in the product storage tank, the filling tube, and in a region surrounding a terminus of the filling tube from which the product is dispensed. The region surrounding the terminus of the filling tube can be partially enclosed, for example, by a casing. Further, the sterile filling environment must be maintained in an area below the terminus of the filling tube, extending as far below the terminus as is necessary to ensure that non-sterile air is effectively prevented from penetrating the area surrounding the terminus of the filling tube.
In order to prevent bacteria from forming in parts of the packaging machine that come into contact with certain liquid foodstuffs it is known to circulate a cleaning fluid through those parts. However, any liquid product remaining in the product tank at the end of the production cycle must be drained from the product tank before the cleaning cycle can begin.
Typically, the remaining product is drained from the product tank by opening the pump valves in the system such that the remaining product flows out of the product tank and into the casing, or where a casing is not provided, onto a draining floor, at atmospheric pressure under the force of gravity. As the remaining liquid product is drained from the product tank in this manner it tends to splash in the casing and becomes unsuitable for reuse. Specifically, the remaining product tends to foam and may become contaminated as it is drained from the product tank. Therefore, the remaining product is disposed of once it is drained from the system. Since packaging machines must be frequently cleaned, regularly disposing of the remaining product is costly.